Biology · May / June 2023 · Paper 62 · Question 1
0610
As printed in the paper
The question as text
Some animals live in cold places. They sometimes huddle together as shown in Fig. 1.1. Fig. 1.1 A student investigated the effect of huddling on heat loss from model animals. Test-tubes containing hot water represented the animals. The student used the method described in step 1 to step 10. Step 1 Place a test-tube in an empty beaker and put a thermometer into the test-tube. Step 2 Approximately half-fill the test-tube with hot water and start the stop-clock. Step 3 After one minute record the temperature of the hot water in the test-tube. Fig. 1.2 is a diagram of part of the thermometer from step 3. 60 °C 70 Fig. 1.2
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Show the answer and mark scheme
1(a)(i)[1]
68.5 (°C) ;
1(a)(ii)[3]
table drawn with at least four, columns / rows and a header line ;
two suitable headings with units ;
all three sets of data recorded (14 values) ;
1(a)(iii)[5]
axes labelled with units ;
suitable linear scale and data occupies at least half the grid in both directions ;
14 points plotted to an accuracy of ± half a small square ; suitable line drawn for each of the three data sets ; key correctly identifies each of the three data sets ;
1(a)(iv)[2]
huddling, reduces heat loss / conserves more heat ; ora the more test-tubes the slower, the temperature drops / heat loss ora
OR
as time increases, temperature falls / heat is lost ;
1(a)(v)[2]
any two from:
(same) size test-tubes ;
(same) type / kind, of test-tubes ;
all test-tubes placed in a beaker ;
(same) total experimental time / described ;
(same) time intervals (between sampling) ;
1(a)(vi)[2]
any two from:
volume of water, not the same / could vary / AW ; temperature (of water) not measured at , start / 0 minutes ; start temperature, not the same / could vary / AW ; no band around 1 test-tube/ bands only on 3 & 7 test-tubes OR no insulating effect in 1 test-tube / band on 3 & 7 test- tubes absorbs heat ;
band tightness, not the same / could vary / AW ;
room / environmental / surrounding, temperature, not the same / could vary / AW ;
1(a)(vii)[2]
any one from:
repeat the whole investigation (at least) twice more / AW ; same volume of water ;
temperature (of water) measured at , start / 0 minutes ; same starting temperature ;
band around 1 test-tube ;
band tightness the same ;
maintain the, room / environmental , temperature ;
1(b)[6]
either – reducing sugar method
independent variable
1
at least three temperature values, tested / stated ; dependent variable
2
time to (first) (correct) colour change (of
Benedict’s) / (correct) colour (of Benedict’s) after a set period of time / mass of precipitate in a fixed time ; 3, 4 and 5 variables kept constant ;;;
concentration of , amylase / enzyme (solution) volume / mass, of, amylase / enzyme (solution) pH
volume of starch (solution) / mass of starch / mass of plant material / size of plant material
concentration of starch (solution)
6, 7 and 8 method ;;;
equilibration (both solutions in water bath before mixing) take (fixed volume of) samples
(testing with) Benedict’s (solution)
use of buffer
use of, colorimeter / colour chart
use of, balance / AW, to measure mass of precipitate method of maintaining temperature
9
repeat investigation twice / at least two replicates ; 10 relevant safety precaution – e.g.
gloves / goggles / tongs / test-tube holder ;
OR disappearance of starch method
independent variable
1
at least three temperature values, tested / stated ; dependent variable
2
time for iodine solution to stay yellow-brown / time for disappearance of starch /
colour of iodine (solution) after a set period of time ; 3, 4 and 5 variables kept constant ;;;
concentration of, amylase / enzyme (solution) volume / mass, of, amylase / enzyme (solution) pH
volume of starch (solution) / mass of starch / mass of plant material / size of plant material
concentration of starch (solution)
6, 7 and 8 method ;;;
equilibration (both solutions in the water bath before mixing)
take samples
(testing with) iodine (solution)
use of, spotting / white, tile
use of buffer
use of, colorimeter / colour chart
method of maintaining temperature
9
repeat investigation twice / at least two replicates ; 10 relevant safety precaution – gloves / goggles ;
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